The invention relates to a process for decontaminating suspensions containing silt pollutants and water, particularly mercury and/hydrocarbon-containing pollutants.
Pollutants, which can be vaporized at temperatures of up to 300.degree. C. are generally driven out of the compound mixture to be decontaminated, such as contaminated silt, in rotary furnaces, in kilns or in a fluidized bed apparatus. Since silt mixtures are generally erosive, all the rotary parts of the known furnaces or apparatus are subject to high wear and require extensive maintenance. In addition, rotary furnaces and fluidized bed apparatus require a uniform generally pelletized material mixture. To provide such a mixture, it is generally necessary to pre-dry the aqueous fractions obtained during the mechanical cleaning procedure. Often, additionally, a vacuum of 0.1 bar or lower pressures are utilized to facilitate the removal of the pollutants. Because of the erosive effects of the material mixture or rather, the silt mixture, the known rotary furnaces and fluidized bed or other apparatus, which include rotary parts and seals, encounter substantial seal problems and, consequently, service problems. For safety reasons the relatively high vacuum utilized with such equipment requires that the equipment is well sealed, but yet the equipment includes large volume apparatus such as rotary furnaces. A collapse of the vacuum generally requires the apparatus to be shut down, repaired and restarted which leads to long downtimes and complex restart problems.
It is therefore the object of the present invention to provide a process for decontaminating suspensions containing silt, pollutants and water wherein the material mixture does not need to be predried and pelletized and furnaces including rotary equipment are also not needed so that the process according to the invention can be performed easily and effectively; it should also be suitable for the cleanup of large volume mixtures or suspensions so that the process can be effectively used for the decontamination of contaminated soils, that is for the protection of the environment.